I used the very high settings tweak for DX9 and the commands I used ontop of that for this were:
sys_physics_CPU 0
fixed_time_step 0.033333
e_particles 0 (all those particles when a box would collide with something killed my GPU)
r_motionblur 4 (need the very high tweak if on DX9)
r_useEdgeAA 2
r_displayinfo 0 (get rid of the white text when in devmode/sandbox)
cl_hud 0
capture_frames 1 (to take a screenshot at every frame so you can add them all together to make a smooth motioned video).